1. Field of the Invention
The present invention relates to a liquid ejection head and an image forming apparatus, and more particularly to a head structure that can be used desirably for preventing drying of ink in a nozzle of an inkjet head and an image forming apparatus having such a head structure.
2. Description of the Related Art
Japanese patent application publication No. 2006-62166 discloses a so-called on-demand type of inkjet recording apparatus. In order to prevent the deterioration of recording qualities caused by increase in the viscosity of ink in nozzles in cases where the ink is not ejected over a long time, this inkjet recording apparatus has a humidification liquid supply port provided in the ejection surface of the recording head, and a moistening region in which the moistening liquid oozing from the humidification liquid supply port is evaporated. In this apparatus, the ejection surface is moistened by evaporation of the moistening liquid in the moistening region.
Japanese patent application publication No. 2007-261204 discloses a liquid ejection head comprising: an air flow supply port which is located near a nozzle and supplies air flow containing moisture of a volatile solvent of ink; and an air flow circulation mechanism which circulates recovered air flow and supplies it again from the air flow supply port.
In the inkjet recording apparatus disclosed in Japanese patent application publication No. 2006-62166, the moistening liquid is supplied to the nozzle surface and evaporation of the moistening liquid produces moistening, but the liquid merely stays in the nozzle surface and does not circulate. Therefore, paper powder, ink mist, and the like gradually accumulate in the moistening region, deteriorating the humidification performance. Further, in cases where a mixed liquid is used for the moistening liquid, a highly-volatile component first evaporates, then the composition of the moistening liquid gradually changes, and therefore, it is difficult to offer stable moistening.
In the liquid ejection head disclosed in Japanese patent application publication No. 2007-261204, the ink ejection direction is changed due to the air flow containing the gaseous volatile liquid, reducing the accuracy of droplet landing.